thymosin and Colonic-Neoplasms

Aberrant expression of thymosin beta4 (Tbeta4) has recently been found to be associated with colorectal carcinoma (CRC) progression evidently due to an increase of the motility and invasion of tumor cells and the induction of a proangiogenic phenotype of endothelial cells. Both mechanisms depend upon matrix-degrading proteases, particularly plasmin and matrix metalloproteinases (MMPs) that are responsible for extensive tissue remodeling. Cleavage of ECM macromolecules weakens the structural integrity of tissues and exposes cryptic domains of extracellular components, which elicit biological responses distinct from intact molecules. Interestingly, signaling via integrins (alphaVbeta3, alpha5beta1) in CRC cells (HT29, CX1.1) is induced by Tbeta4 and VEGF-A only when they grow in 3D fibrin gels but not in 2D ones. The cells growing in 3D fibrin gels release upon Tbeta4 significant amounts of active MMPs (MMP-2, MMP-9, and MMP-7) that cause extensive proteolysis in their close vicinity. As evidenced by a variety of approaches (transfection experiments, coimmunoprecipitation, gene silencing with siRNA), we found that this involves interaction of Tbeta4 with Ku80, which has recently been described by us to mediate Tbeta4 intracellular activity.

Topics: Cell Movement; Cells; Colonic Neoplasms; Endothelial Cells; Extracellular Matrix; Humans; Integrins; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinases; Neoplasms; RNA, Small Interfering; Signal Transduction; Thymosin; Vascular Endothelial Growth Factor A

Colorectal cancer (CRC) affects millions of people worldwide. Chemoresistance seriously impairs the therapeutic effects. Lipid droplets (LDs) abnormally accumulate in CRC supported chemoresistance. Exploring the mechanism of LD-induced chemoresistance is extremely important for improving prognosis of CRC patients. The expression of PTMA was increased in both CRC tissues and cells, which was positively correlated with LD production. PTMA facilitated chemoresistance to gemcitabine by inducing LD production in CRC cells. PTMA enhanced LD biogenesis and chemoresistance to gemcitabine by promoting SREBP-1-mediated lipogenesis and STAT3 activation in CRC.

Topics: Acetylation; Caco-2 Cells; Cell Line, Tumor; Colonic Neoplasms; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; HCT116 Cells; HT29 Cells; Humans; Lipid Droplets; Lipogenesis; Prognosis; Protein Precursors; STAT3 Transcription Factor; Sterol Regulatory Element Binding Protein 1; Thymosin; Up-Regulation

Increasing evidence showed invariant NKT cells (iNKT cell) are an attractive candidate for cancer immunotherapy, but its role in colorectal cancer treatment was still unclear. Here we reported iNKT cells exerted moderate cytotoxic effect against colorectal cancer cells (CRC cells) with the stimulation of α-Galcer, and the mutual recognition between CRC and iNKT cells could be greatly enhanced by Thymosinα1 (TA), which resulted in stronger killing efficiency both in vitro and in vivo. TA is widely used as an immune adjuvant for cancer therapy, but how it works on cancer cells still remains unclear. We found TA could upregulate CD80, B7H2 and CD1d expression on CRC cells. However, neutralization assay revealed iNKT cells' activation depended on CD1d expression rather than CD80 or B7H2. Moreover, colon cancer stem cells expressed higher CD1d level, which accounted for their greater sensitization to iNKT cells. Mechanistically, inhibition of Erk/MAPK pathway greatly attenuated the upregulation of CD1d by TA. Taken together, depending on Erk/MAPK pathway, TA promoted the activation and cytotoxicity of iNKT cells via upregulating CD1d expression on CRC cells, which indicated a novel immunotherapeutic strategy of iNKT cells against CRC.

Topics: Animals; Antigens, CD1d; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Proliferation; Coculture Techniques; Colonic Neoplasms; Female; Flow Cytometry; Fluorescent Antibody Technique; Humans; Immunoenzyme Techniques; Mice; Mice, Inbred NOD; Mice, SCID; Natural Killer T-Cells; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thymalfasin; Thymosin; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Thymosin beta 4 (Tβ4) is a ubiquitous peptide that plays pivotal roles in the cytoskeletal system and in cell differentiation. Recently, a role for Tβ4 has been proposed in experimental and human carcinogenesis, including gastrointestinal cancer. This study was aimed at evaluating the relationship between Tβ4 immunoreactivity and the initial steps of carcinogenesis.. In total, 60 intestinal biopsies, including 10 hyperplastic polyps, 10 sessile serrated adenomas/polyps, 15 colorectal adenomas with low-grade dysplasia, 15 adenomas with high-grade dysplasia, 15 adenocarcinomas and 10 samples of normal colon mucosa, were analyzed for Tβ4 expression by immunohistochemistry.. Weak cytoplasmic reactivity for Tβ4 was detected in the normal colon mucosa. No reactivity for Tβ4 was found in hyperplastic and sessile serrated polyps/adenomas. Tβ4 expression was observed in 10/15 colorectal adenocarcinomas. In adenomas with low-grade dysplasia, Tβ4 immunoreactivity was mainly detected in dysplastic glands but was absent in hyperplastic glands. Tβ4 immunoreactivity was characterized by spot-like perinuclear staining. In high-grade dysplastic polyps, immunostaining for Tβ4 appeared diffuse throughout the entire cytoplasm of dysplastic cells. Spot-like perinuclear reactivity was detected in adenocarcinoma tumor cells.. Our study shows for the first time that Tβ4 is expressed during different steps of colon carcinogenesis. The shift of Tβ4 immunolocalization from low-grade to high-grade dysplastic glands suggests a role for Tβ4 in colorectal carcinogenesis. However, the real meaning of Tβ4 reactivity in dysplastic intestinal epithelium remains unknown.

Topics: Adenoma; Biopsy; Cell Differentiation; Colon; Colonic Neoplasms; Colonic Polyps; Disease Progression; Female; Humans; Immunohistochemistry; Male; Neoplasm Proteins; Thymosin

Thymosin β(4) (Tβ(4)) overexpression increases cell migration and tumor metastasis. Hence, understanding the mechanism of cancer cell migration induced by Tβ(4) may provide means to inhibit their metastasis. We demonstrated higher Rac1 activities and expression levels of IQGAP1 and ILK in highly migrated Tβ(4)-overexpressing SW480 cells. In addition, IQGAP1 formed a complex with ILK and knockdown of Tβ(4) simultaneously reduced ILK and IQGAP1 protein levels as well as their migration ability. These findings suggest that Tβ(4) increases migration of colon cancer cells via activating Rac1 by elevating IQGAP1/ILK complexes and IHC results illustrated a similar mechanism occurring in vivo.

Topics: Animals; Blotting, Western; Cell Line, Tumor; Cell Movement; Colonic Neoplasms; Humans; Mice; Neoplasm Metastasis; Protein Serine-Threonine Kinases; rac1 GTP-Binding Protein; ras GTPase-Activating Proteins; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Thymosin; Tumor Cells, Cultured; Up-Regulation

Thymosin β(4) (Tβ(4)), overexpressed in various tumors, has been shown to be involved in cellular anti-oxidation. Reactive oxygen species (ROS) function as signaling molecules and play certain roles in tumor progression. To assess the anti-oxidative role of endogenous Tβ(4) in tumor cells, its expression in SW480 cells was knocked down by a shRNA, which induced significant increases of ROS. Interestingly, some cristae-lost and several electron-dense mitochondria appeared in cells with Tβ(4) knockdown that was accompanied by a marked decline of the membrane potential of these organelles. Strikingly, while the ATP and lactate levels in SW480 cells were notably elevated by Tβ(4) downregulation, this treatment significantly diminished the mitochondrial DNA copy number and protein levels of several subunits of the electron transport complexes. Finally, immunofluorescent staining results suggested the presence of Tβ(4) in mitochondria. To the best of our knowledge, this is the first report to demonstrate that Tβ(4) knockdown can disrupt the morphology and some crucial functions of mitochondria in human colorectal carcinoma (CRC) cells.

Topics: Cell Line, Tumor; Colonic Neoplasms; Gene Knockdown Techniques; Glycolysis; Humans; Mitochondria; Reactive Oxygen Species; Thymosin

Thymosin β4 (Tβ4) is an actin-binding peptide overexpressed in several tumors, including colon carcinomas. The aim of this study was to investigate the role of Tβ4 in promoting the tumorigenic properties of colorectal cancer stem cells (CR-CSCs), which are responsible for tumor initiation and growth. We first found that CR-CSCs from different patients have higher Tβ4 levels than normal epithelial cells. Then, we used a lentiviral strategy to down-regulate Tβ4 expression in CR-CSCs and analyzed the effects of such modulation on proliferation, survival, and tumorigenic activity of CR-CSCs. Empty vector-transduced CR-CSCs were used as a control. Targeting of the Tβ4 produced CR-CSCs with a lower capacity to grow and migrate in culture and, interestingly, reduced tumor size and aggressiveness of CR-CSC-based xenografts in mice. Moreover, such loss in tumorigenic activity was accompanied by a significant increase of phosphatase and tensin homologue (PTEN) and a concomitant reduction of the integrin-linked kinase (ILK) expression, which resulted in a decreased activation of protein kinase B (Akt). Accordingly, exogenous expression of an active form of Akt rescued all the protumoral features lost after Tβ4 targeting in CR-CSCs. In conclusion, Tβ4 may have important implications for therapeutic intervention for treatment of human colon carcinoma.

Topics: Animals; Cell Differentiation; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cells, Cultured; Colonic Neoplasms; Down-Regulation; Epithelial Cells; Gene Expression Regulation, Neoplastic; Humans; Lentivirus; Mice; Mice, SCID; Neoplastic Stem Cells; Oncogene Protein v-akt; Protein Serine-Threonine Kinases; PTEN Phosphohydrolase; Thymosin

Thymosin β4 has multi-functional roles in cell physiology, but little is known about its mechanism(s) of action. We previously reported that thymosin β4 stimulated angiogenesis through the induction of vascular endothelial growth factor (VEGF). To identify the mechanism of VEGF induction by thymosin β4, we have used a luciferase assay system with VEGF in the 5' promoter region. We also analyzed the effect of thymosin β4 on VEGF mRNA stability and on the expression and stability of hypoxia-inducible factor (HIF)-1α. We found that thymosin β4 induces VEGF expression by an increase in the stability of HIF-1α protein. Analysis of the expression patterns of thymosin β4 and HIF-1α in colon cancer tissue microarray showed that thymosin β4 and HIF-1α co-localized in these biopsies. These data show that thymosin β4 induces the expression of VEGF indirectly by increasing the protein stability of HIF-1α.

Topics: Animals; Biopsy; Blotting, Western; Cell Line, Tumor; Colon; Colonic Neoplasms; Female; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Luciferases; Male; Mice; Mice, Inbred C57BL; Microscopy, Confocal; Promoter Regions, Genetic; Protein Stability; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thymosin; Tissue Array Analysis; Vascular Endothelial Growth Factor A

The epithelial-mesenchymal transition (EMT) is crucial for the invasion and metastasis of many epithelial tumors including colorectal carcinoma (CRC). In the present study, a scattering and fibroblastic morphology with reduced intercellular contacts was found in the SW480 colon cancer cells overexpressing the gene encoding thymosin beta4 (Tbeta4), which was accompanied by a loss of E-cadherin as well as a cytosolic accumulation of beta-catenin, two most prominent markers of EMT. Whereas E-cadherin downregulation was likely to be accounted by a ZEB1-mediated transcriptional repression, the accumulation of beta-catenin was a result of glycogen synthase kinase-3beta inactivation mediated by integrin-linked kinase (ILK) and/or its downstream effector, Akt. Intriguingly, ILK upregulation in Tbeta4-overexpressing SW480 cells seemed to be attributed mainly to a stabilization of this kinase by complexing with particularly interesting new Cys-His protein (PINCH) more efficiently. In the meantime, a strong correlation between the expression levels of Tbeta4, ILK and E-cadherin in CRC patients was also revealed by immunohistochemical analysis. Taken together, these data suggest a novel role of Tbeta4 in promoting CRC progression by inducing an EMT in tumor cells via upregulating ILK and consequentially its signal transduction.

Topics: Adaptor Proteins, Signal Transducing; Animals; beta Catenin; Cadherins; Casein Kinase I; Colonic Neoplasms; Colorectal Neoplasms; DNA-Binding Proteins; Enzyme Inhibitors; Epithelial Cells; Fibroblasts; Glycogen Synthase Kinase 3; Homeodomain Proteins; Humans; Immunoenzyme Techniques; LIM Domain Proteins; Membrane Proteins; Mesoderm; Mice; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Serine-Threonine Kinases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Antisense; RNA, Messenger; Signal Transduction; Thymosin; Transcription Factors; Transcription, Genetic; Transfection; Tumor Cells, Cultured; Up-Regulation; Zinc Finger E-box-Binding Homeobox 1

To investigate the effects of thymosin alpha1 (Talpha1) on the differentiation, maturation and function of tumor lysate-pulsed dendritic cells (LyDCs) in vitro, and to study the antitumor effects on tumor models of the nude mice bearing colon cancer in vivo.. Immature DCs (imDCs) were prepared routinely from human peripheral blood mononuclear cells. The LyDCs were prepared from the imDCs loaded with lysate of HT-29 tumor cell line. The phenotypes of imDCs and LyDCs pre- or post-stimulated by Talpha1 were analyzed by flow cytometry. Autologous T cells were cocultured with LyDCs in the presence or absence of Talpha1 2 days later. IL-12 secretion of LyDCs and IFN-gamma secretion of the activated T cells in the supernatants were measured by ELISA. The in vitro cytotoxicity of antigen specific cytotoxic T lymphocytes (CTLs) induced by LyDCs which were treated with Talpha1 was evaluated by MTT assay. A humanized nude mice model bearing colon cancer was established. The in vivo antitumor activity was evaluated in the humanized nude mice after the treatment with LyDCs plus Talpha1 or LyDCs alone.. The expression levels of HLA-DR, CD80, CD86 and CD83 in imDCs and LyDCs were markedly up-regulated after the stimulation with Talpha1 respectively (P<0.01). The levels of IL-12 and IFN-gamma were also significantly increased in the presence of Talpha1 (P<0.05 and P<0.01, respectively). Cytotoxicity induced by LyDCs treated with Talpha1 was significantly enhanced (P<0.01) as compared with LyDCs in vitro. The humanized cellular immunity was successfully established in the nude mice model. On the 58 th day after the inoculation of tumor cells, the inhibitory rate of tumor growth was significantly higher in the group treated with LyDCs plus Talpha1 than that in the group treated with LyDCs alone (60.41% and 37.20%, respectively; P<0.01).. Talpha1 can induce the functional maturation of DCs and enhance the immune response of CD4+Th1 arm and cytotoxicity induced by LyDCs. Talpha1 has a synergistic antitumor effect. It might be a promising adjuvant candidate for DC-based immunotherapy of gastrointestinal carcinomas.

Topics: Animals; Antineoplastic Agents; Cell Extracts; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Dendritic Cells; Female; Humans; Immunotherapy; Interferon-gamma; Interleukin-12; Mice; Mice, Nude; T-Lymphocytes, Cytotoxic; Thymalfasin; Thymosin

Thymosin beta-4 (Tbeta-4), a small peptide originally isolated from calf thymus, modulates the formation of F-actin microfilaments by sequestering the monomeric G-actin. Recent studies have shown that overexpression of the Tbeta-4 gene occurs not only in many human carcinomas but also in the highly metastatic melanomas and fibrosarcomas. However, little is known about the specific growth advantages acquired by different tumors from this genetic abnormality. To address the above questions, Tbeta-4-overexpressing human colon carcinoma (SW480) cells were established by stable transfection and their phenotypic changes were monitored. We found that both the morphology and the cortical actin cytoskeleton of SW480 cells were altered by Tbeta-4 overexpression. Moreover, both cellular level and that distributed over the intercellular junctions of the E-cadherin were decreased in the Tbeta-4 overexpressers, which were accompanied by a twofold increase in their saturation densities. Meanwhile, these cells also exhibited an increased ability to form colonies in soft agar. Interestingly, a dramatic increase of growth rate was detected in the Tbeta-4 overexpressers, which might be attributed to an accelerated proliferation induced by c-Myc that was activated by nuclear beta-catenin. Finally, a motility increase of these cells was demonstrated by two independent migration assays, which was accompanied by an enhanced focal contact. Taken together, our data suggest that the drastic growth property and motility changes of the SW480 cells overexpressing Tbeta-4 gene are due mainly to a deregulated cell-cell adhesion arisen from the downregulation of E-cadherin, plus uncontrolled cell proliferation owing to the upregulation of beta-catenin, both resulted from a breakdown of actin microfilaments caused by the overexpression of this G-actin sequestering peptide.

Topics: beta Catenin; Cadherins; Carcinoma; Cell Division; Cell Movement; Colonic Neoplasms; Cytoskeletal Proteins; Disease Progression; Focal Adhesions; Humans; Proto-Oncogene Proteins c-myc; Thymosin; Trans-Activators; Transfection; Tumor Cells, Cultured; Tumor Stem Cell Assay

VPF/VEGF acts selectively on the vascular endothelium to enhance permeability, induce cell migration and division, and delay replicative senescence. To understand the changes in gene expression during endothelial senescence, we investigated genes that were differentially expressed in early vs. late passage (senescent) human dermal endothelial cells (HDMEC) using cDNA array hybridization. Early passage HDMEC cultured with or without VPF/VEGF overexpressed 9 and underexpressed 6 genes in comparison with their senescent counterparts. Thymosin beta-10 expression was modulated by VPF/VEGF and was strikingly down-regulated in senescent EC. The beta-thymosins are actin G-sequestering peptides that regulate actin dynamics and are overexpressed in neoplastic transformation. We have also identified senescent EC in the human aorta at sites overlying atherosclerotic plaques. These EC expressed senescence-associated neutral beta-galactosidase and, in contrast to adventitial microvessel endothelium, exhibited weak staining for thymosin beta-10. ISH performed on human malignant tumors revealed strong thymosin beta-10 expression in tumor blood vessels. This is the first report that Tbeta-10 expression is significantly reduced in senescent EC, that VPF/VEGF modulates thymosin beta-10 expression, and that EC can become senescent in vivo. The reduced expression of thymosin beta-10 may contribute to the senescent phenotype by reducing EC plasticity and thus impairing their response to migratory stimuli.

Topics: Actins; Adenocarcinoma; Aorta, Thoracic; Arteriosclerosis; Cells, Cultured; Cellular Senescence; Colonic Neoplasms; DNA, Complementary; Endothelial Growth Factors; Endothelium, Vascular; Gene Expression Regulation; Humans; Infant, Newborn; Lymphokines; Male; Microcirculation; RNA, Messenger; Skin; Thymosin; Transcription, Genetic; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

The beta-thymosins comprise a family of structurally related, highly conserved acidic polypeptides, originally isolated from calf thymus. Recently, we have demonstrated the overexpression of thymosin beta-10 (TB10) in rat thyroid transformed cell lines and in human thyroid carcinoma tissues and cell lines. To verify whether TB10 overexpression is a general event in the process of carcinogenesis, we have analyzed TB10 mRNA levels in human colon carcinomas, germ cell tumors of different histological types, breast carcinomas, ovarian carcinomas, uterine carcinomas, colon and esophageal carcinoma cell lines. Overexpression of the TB10 gene was detected in all of the neoplastic tissues and cell lines compared to the respective normal tissues. Moreover, the mouse model of skin carcinogenesis induced by the combined action of chemical carcinogens and phorbol esters was used to identify the stage of TB10 gene induction. The expression was almost undetectable in normal keratinocytes, its induction occurred even at the papilloma stage, however a further increased expression was observed in the carcinoma derived cell lines. Finally, immunohistochemical analysis of some breast, colon and ovary carcinoma samples by using specific anti-TB10 antibodies revealed the presence of the TB10 protein in all of the neoplastic tissues, but not in the respective normal tissues. Therefore the TB10 detection may be considered a potential tool for the diagnosis of several human neoplasias.

Topics: Animals; Breast Neoplasms; Carcinoma; Colonic Neoplasms; Esophageal Neoplasms; Female; Gene Expression; Germinoma; Humans; Immunohistochemistry; Male; Mice; Neoplasms; Ovarian Neoplasms; RNA; Skin Neoplasms; Testicular Neoplasms; Thymosin; Tumor Cells, Cultured; Uterine Neoplasms

The effects of prothymosin alpha1 (Pro alpha1) in combination with interleukin-2 (IL-2) on peripheral blood lymphocytes from 50 colorectal tumor patients at different stages were studied with respect to immunocytotoxicity, adhesion to cultured SW620 colon carcinoma cells, secretion of cytokines and expression of adhesion and surface marker molecules. On average, the patients showed lower natural killer (NK) cell activity than healthy donors, which was associated with a lower adhesion capacity to the tumor target cells. The NK cell activity of the patients was inversely related to the tumor stage. The generation of lymphokine(IL-2)-activated killer (LAK) cell activity was found to be comparable on lymphocytes from healthy individuals and patients and was not correlated to tumor stage. Pro alpha1 stimulated patients' LAK cell activity only, primarily at the early stage (Dukes A/B). The Pro alpha1 effect was associated with an increased adhesion of lymphocytes to tumor target cells and an increased secretion of the deficient IL-2-induced IFN gamma secretion. No significant effects on the low level of TNF alpha secretion was noted. By flow cytometry, Pro alpha1 in combination with IL-2 augmented the expression of the NK cell markers CD56, CD16/56, the subset CD3/16/56 and CD25 on lymphocytes of the patients. In contrast, Pro alpha1 was equally effective by increasing the expression of CD18 and CD11a on lymphocytes from the patients and from normal controls. In conclusion, Pro alpha1, in combination with IL-2, can partially normalize lymphocyte deficiencies of colon cancer patients in vitro. This potential might provide an experimental basis for applying Pro alpha1 or related thymic peptides in selected immunotherapies against colorectal tumors.

Topics: Adult; Aged; Aged, 80 and over; Cell Adhesion; Colonic Neoplasms; Colorectal Neoplasms; Cytotoxicity, Immunologic; Female; Humans; Immunotherapy, Adoptive; Interleukin-2; Killer Cells, Lymphokine-Activated; Killer Cells, Natural; Lymphocytes; Male; Middle Aged; Neoplasm Staging; Protein Precursors; Thymosin; Tumor Cells, Cultured

Thymosin alpha 1 (T alpha 1) is an immune modulatory peptide which has been evaluated in a variety of clinical trials. Although no in vivo adverse effects, including enhancement of tumor growth, have been noted, in vitro studies suggesting a role for T alpha 1 in cell growth have been reported. The studies presented in this report evaluated both exogenously added T alpha 1 and endogenously expressed T alpha 1 as factors which could either promote growth of tumor cells or induce transformation. No effect of exogenous T alpha 1 on cell growth was found. NIH-3T3 cells transfected with cDNA for the precursor ProThymosin alpha (Pro T alpha) expressed elevated levels of authentic T alpha 1 but did not demonstrate either enhanced proliferation in liquid culture or transformation as defined by the loss of contact inhibition or anchorage independent growth in soft agar. Thus these studies argue against the hypothesis that T alpha 1 is either an intracellular or extracellular growth promoter.

Topics: 3T3 Cells; Adenocarcinoma; Animals; Breast Neoplasms; Cecal Neoplasms; Cell Division; Cell Transformation, Neoplastic; Colonic Neoplasms; Growth Substances; Ileal Neoplasms; Mice; Protein Precursors; Thymosin; Tumor Cells, Cultured

Prothymosin alpha (PT-alpha) is a nuclear protein involved in cell proliferation. Transcription of PT-alpha has been reported to be regulated by the c-myc gene in vitro. We identified PT-alpha as being overexpressed in a human colon cancer minus normal mucosa subtraction cDNA library. Northern blot (messenger RNA) analysis showed that both PT-alpha and c-myc genes were overexpressed in human colorectal cancers compared with adjacent normal tissues. Immunohistochemical studies for PT-alpha and c-myc supported these findings. There was no correlation between PT-alpha or c-myc messenger RNA expression and Dukes' stage of colorectal cancer; or between either of these two and actin messenger RNA expression. There was, however, a significant correlation between the PT-alpha expression and c-myc expression (P < 0.001). These findings support the hypothesis that PT-alpha gene transcription may be associated with, and possibly under the control of, the c-myc gene in human colorectal cancers.

Topics: Blotting, Northern; Colon; Colonic Neoplasms; Humans; Liver Neoplasms; Protein Precursors; Proto-Oncogene Proteins c-myc; RNA, Messenger; Thymosin

We constructed a "non-metastatic cell (SW837)--metastatic cell (PMCO1)" subtraction library and identified one cDNA that was strongly expressed in SW837 but weakly expressed in PMCO1. The nucleotide sequence of the cDNA revealed that it encoded thymosin beta-4. Four non-metastatic cell lines, which produced no experimental liver metastasis in nude mice, showed high expression of thymosin beta-4. However three of four metastatic cell lines showed weak expression of thymosin beta-4. Among surgical materials, thymosin beta-4 expression was high in tumors without metastasis in comparison with non-tumorous mucosa, but one case with liver metastasis showed decreased expression in both the primary and metastatic tumors. We suspect that down-regulation of thymosin beta-4 expression is correlated with the metastatic capacity of colorectal carcinomas.

Topics: Animals; Colonic Neoplasms; Colorectal Neoplasms; DNA, Neoplasm; Gene Expression; Gene Library; Humans; Mice; Mice, Nude; Neoplasm Transplantation; RNA, Messenger; Thymosin; Transplantation, Heterologous; Tumor Cells, Cultured

Topics: Adenocarcinoma; Animals; BCG Vaccine; Bronchial Neoplasms; Colonic Neoplasms; Corynebacterium Infections; Humans; Immunotherapy; Levamisole; Melanoma; Neoplasms; Propionibacterium acnes; RNA, Neoplasm; Sheep; Thymosin